Collaborative Data Objects heap corruption occurs when you try to access an Exchange mailbox

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Microsoft ended support for Office 2003 on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article has been archived. It is offered "as is" and will no longer be updated.
For a Microsoft Exchange 2000 Server version of this article, see 824960.

For a Microsoft Exchange Server 5.5 version of this article, see 818709.
When you use a third-party program that uses Collaborative Data Objects (CDO) 1.21 to access a mailbox on a computer that is running Microsoft Exchange Server 2003, the third-party program may stop responding.
This problem occurs when you try to access a user account that was previously accessed by a client computer that is running Microsoft Office Outlook 2003.

Outlook 2003 adds a fourth entry to PR_FREEBUSY_ENTRYIDS, a MAPI property with multiple values that is stored on the Inbox folder. Collaborative Data Objects (CDO) 1.21 only expects three entries. This causes heap corruption that causes the third-party program to stop responding.

Hotfix Information

You can download this hotfix from the Microsoft Download Center. To do so, visit the following Microsoft Web site:


There are no prerequisites.

Restart Requirement

You do not have to restart your computer after you apply this hotfix.

Hotfix Replacement Information

This hotfix does not replace any other hotfixes.

File Information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Date         Time   Version         Size     File name------------------------------------------------------------03-Jun-2003  19:12  6.5.6980.3      708,096  Cdo.dll          
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Article ID: 823343 - Last Review: 12/08/2015 03:22:20 - Revision: 7.9

Microsoft Exchange Server 2003 Standard Edition, Microsoft Exchange Server 2003 Enterprise Edition, Microsoft Office Outlook 2003

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